Ch_3_SG_020308 - BIO 105 Ch 3(Cell Structure Function...

BIO 105 Ch. 3 (Cell Structure & Function) Sunday, February 3, 20083.1 Cellular level of organization•Cells are the smallest unit of life–Exhibit all characteristics of life–All cells are highly organized–Many cells become specialized for complex functions•Cell theory–All living things are composed of cells–Cells are the functional and structural units of organisms–All cells are derived from previously existing cells•Discovery of cells–Antonie van Leeuwenhoek- invented the light microscope–Robert Hooke- first observed cells in cork–Schleiden and Schwann-proposed cell theory•Cell size–Most cells are smaller than 1 mm in diameter–Surface/volume ratio determines cell size•Volume increases as the cube of the radius while surface area increases by the square of the radius•Therefore small cells have a greater surface/volume ratio than larger cells•Nutrients from the environment must cross the surface of the cell to enter•Cells must be small in order for the surface area to be adequate to supply nutrients3.2 Eukaryotic cells•Eukaryotic cells have a membrane-bound nucleus–Nucleus contains genetic material–All plant and animal cells are eukaryotic•Plasma membrane-outer boundary of cell–Phospholipid bilayer-note arrangement of hydrophilic and hydrophobic ends–Embedded proteins–Associated glycolipids and cholesterol•Functions of the cell membrane–Functions as a barrier between the cell and its environment–Plays a role in regulation of transport of substances into and out of the cell–Contains receptors that determine how a cell will respond to stimuli in the environment–

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